Megawite
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Helen D. Megaw
Formula:
CaSnO3
Colour:
Pale yellowish brown, pale yellow to colourless
Lustre:
Vitreous
Specific Gravity:
5.06 (Calculated)
Crystal System:
Orthorhombic
Name:
It is named in honour of the British crystallographer Helen Dick Megaw (1 June 1907, Dublin, Ireland - 26 February 2002, Ballycastle, Northern Ireland) who made significant contributions to our understanding of the structure and properties of natural and synthetic perovskites. In 1989, Megaw became the first woman to receive the Roebling Medal of the Mineralogical Society of America.
Type Locality:
Isostructural with:
Classification of Megawite
Approved
Approval Year:
2010
4.CC.30
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
C : Metal: Oxygen = 2: 3,3: 5, and similar
C : With large and medium-sized cations
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
C : Metal: Oxygen = 2: 3,3: 5, and similar
C : With large and medium-sized cations
Physical Properties of Megawite
Vitreous
Transparency:
Transparent
Colour:
Pale yellowish brown, pale yellow to colourless
Streak:
White
Cleavage:
Distinct/Good
on {110} and {001}
on {110} and {001}
Density:
5.06 g/cm3 (Calculated)
Optical Data of Megawite
Type:
Biaxial
RI values:
n = 1.89
Max Birefringence:
δ = 0.000
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Very High
Chemical Properties of Megawite
Formula:
CaSnO3
Elements listed:
Crystallography of Megawite
Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:
Pban
Cell Parameters:
a = 5.56(3) Å, b = 5.71(3) Å, c = 7.943(3) Å
Ratio:
a:b:c = 0.974 : 1 : 1.391
Unit Cell V:
252.17 ų (Calculated from Unit Cell)
Z:
4
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.984 | (52) |
| 3.970 | (19) |
| 2.855 | (43) |
| 2.812 | (100) |
| 2.780 | (19) |
| 1.992 | (13) |
| 1.985 | (13) |
| 1.640 | (13) |
Type Occurrence of Megawite
General Appearance of Type Material:
Either pseudo-cubic or pseudo-cuboctahedral crystals do not exceed 15 µm in size and usually occur as inclusions in spurrite (xenolith No. 1). Megawite forms rims on µm-sized lakargiite crystals in larnite-cuspidine zones in skarns which contain abundant
Place of Conservation of Type Material:
Mineralogical Museum of Wrocław University, Poland under accession number MMUWrII16 717 and the Fersman Mineralogical Museum, Moscow, Russia under accession number4021/1.
Geological Setting of Type Material:
It was found in the spurrite zone of skarned xenolith no. 1
(20-25 m in size) in ignimbrite.
Associated Minerals at Type Locality:
Synonyms of Megawite
Relationship of Megawite to other Species
Other Members of this group:
| Barioperovskite | BaTiO3 | Orth. mm2 : Amm2 |
| Isolueshite | (Na,La)NbO3 | Iso. m3m (4/m 3 2/m) : Pm3m |
| Loparite-(Ce) | (Na,REE)Ti2O6 | |
| Lueshite | NaNbO3 | Orth. mmm (2/m 2/m 2/m) |
| Macedonite | PbTiO3 | Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm |
| Perovskite | CaTiO3 | Orth. mmm (2/m 2/m 2/m) : Pnma |
| Tausonite | SrTiO3 | Iso. 4 3m |
Related Minerals - Nickel-Strunz Grouping
| 4.CC. | Allendeite | Sc4Zr3O12 | Trig. 3 : R3 |
| 4.CC. | Yttriaite-(Y) | Y2O3 | Iso. |
| 4.CC.05 | Chrombismite | Bi16CrO27 | Tet. |
| 4.CC.10 | Freudenbergite | Na2(Ti,Fe)8O16 | Mon. |
| 4.CC.15 | Grossite | CaAl4O7 | Mon. 2/m : B2/b |
| 4.CC.20 | Chlormayenite | Ca12Al14O32[◻4Cl2] | Iso. 4 3m : I4 3d |
| 4.CC.25 | Yafsoanite | Ca3Zn3(TeO6)2 | Iso. m3 (2/m 3) |
| 4.CC.30 | Latrappite | Ca2NbFe3+O6 | Orth. mmm (2/m 2/m 2/m) : Pnma |
| 4.CC.30 | Lueshite | NaNbO3 | Orth. mmm (2/m 2/m 2/m) |
| 4.CC.30 | Natroniobite | NaNbO3 | Mon. |
| 4.CC.30 | Perovskite | CaTiO3 | Orth. mmm (2/m 2/m 2/m) : Pnma |
| 4.CC.30 | Barioperovskite | BaTiO3 | Orth. mm2 : Amm2 |
| 4.CC.30 | Lakargiite | Ca(Zr,Sn,Ti)O3 | Orth. mmm (2/m 2/m 2/m) : Pnma |
| 4.CC.35 | Loparite-(Ce) | (Na,REE)Ti2O6 | |
| 4.CC.35 | Macedonite | PbTiO3 | Tet. 4/mmm (4/m 2/m 2/m) : P4/nmm |
| 4.CC.35 | Tausonite | SrTiO3 | Iso. 4 3m |
| 4.CC.35 | Isolueshite | (Na,La)NbO3 | Iso. m3m (4/m 3 2/m) : Pm3m |
| 4.CC.40 | Crichtonite | Sr(Mn,Y,U)Fe2(Ti,Fe,Cr,V)18(O,OH)38 | Trig. 3 : R3 |
| 4.CC.40 | Davidite-(Ce) | (Ce,La)(Y,U,Fe)(Ti,Fe)20(O,OH)38 | Trig. 3 : R3 |
| 4.CC.40 | Davidite-(La) | (La,Ce)(Y,U,Fe)(Ti,Fe)20(O,OH)38 | Trig. |
| 4.CC.40 | Davidite-(Y) | (La,Ce,Na,Ca,Pb)(Y,Fe2+,◻)(Fe2+,Mn2+)2(Ti,Fe3+,Nb,Zr)18O38 (hypothetical) | Trig. |
| 4.CC.40 | Landauite | NaMnZn2(Ti,Fe)6Ti12O38 | Trig. 3 : R3 |
| 4.CC.40 | Lindsleyite | (Ba,Sr)(Zr,Ca)(Fe,Mg)2(Ti,Cr,Fe)18O38 | Trig. |
| 4.CC.40 | Loveringite | (Ca,Ce,La)(Zr,Fe)(Mg,Fe)2(Ti,Fe,Cr,Al)18O38 | Trig. |
| 4.CC.40 | Mathiasite | (K, Ba, Sr)(Zr, Fe)(Mg,Fe)2 (Ti,Cr,Fe)18O38 | Trig. |
| 4.CC.40 | Senaite | Pb(Mn,Y,U)(Fe,Zn)2(Ti,Fe,Cr,V)18(O,OH)38 | Trig. |
| 4.CC.40 | Dessauite-(Y) | (Sr,Pb)(Y,U)(Ti,Fe3+)20O38 | Trig. 3 : R3 |
| 4.CC.40 | Cleusonite | (Pb,Sr)(U4+,U6+)(Fe2+,Zn)2(Ti,Fe2+,Fe3+)18(O,OH)38 | Trig. 3 : R3 |
| 4.CC.40 | Gramaccioliite-(Y) | (Pb,Sr)(Y,Mn)Fe3+2(Ti,Fe3+)18O38 | Trig. 3 |
| 4.CC.45 | Diaoyudaoite | NaAl11O17 | Hex. |
| 4.CC.45 | Hawthorneite | BaMgTi3Cr4Fe2+2Fe3+2O19 | Hex. 6/mmm (6/m 2/m 2/m) : P63/mmc |
| 4.CC.45 | Hibonite | (Ca,Ce)(Al,Ti,Mg)12O19 | Hex. |
| 4.CC.45 | Lindqvistite | Pb2Mn2+Fe16O27 | Hex. |
| 4.CC.45 | Magnetoplumbite | (Pb,Mn)(Fe,Mn)12O19 | Hex. |
| 4.CC.45 | Plumboferrite | Pb2(Fe3+,Mn2+,Mg)11O19 | Trig. 3 2 |
| 4.CC.45 | Yimengite | K(Cr,Ti,Fe,Mg)12O19 | Hex. |
| 4.CC.45 | Haggertyite | BaFe2+4Fe3+2Ti5MgO19 | Hex. 6/mmm (6/m 2/m 2/m) : P63/mmc |
| 4.CC.45 | Nežilovite | PbZn2Mn4+2Fe3+8O19 | Hex. 6/mmm (6/m 2/m 2/m) : P63/mmc |
| 4.CC.45 | Batiferrite | BaTi2Fe3+8Fe2+2O19 | Hex. |
| 4.CC.45 | Hibonite-(Fe) | (Fe,Mg)Al12O19 | Hex. 6/mmm (6/m 2/m 2/m) : P63/mmc |
| 4.CC.45 | Barioferrite | BaFe3+12O19 | Hex. 6/mmm (6/m 2/m 2/m) : P63/mmc |
| 4.CC.50 | Jeppeite | (K,Ba)2(Ti,Fe)6O13 | Mon. |
| 4.CC.55 | Zenzénite | Pb3Fe4Mn3O15 | Hex. |
| 4.CC.60 | Mengxianminite (of Huang et al.) | (Ca,Na)3(Fe,Mn)2Mg2(Sn,Zn)5Al8O29 |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
References for Megawite
Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Galuskin, E.V., Galuskina, I.O., Gazeev, V.M., Dzierżanowski, P., Prusik, K., Pertsev, N.N., Zadov, A.E. & Gurbanov, A.G. (2010): Megawite CaSnO3 - a new mineral of the perowskite group. 20th General Meeting of the IMA (IMA2010), Budapest, Hungary, August 21-27, CD of Abstracts, p. 444.
Galuskin, E.V., Galuskina, I.O., Gazeev, V.M., Dzierżanowski, P., Prusik, K., Pertsev, N.N., Zadov, A.E., Bailau, R. & Gurbanov, A.G. (2011): Megawite, CaSnO3: a new perovskite-group mineral from skarns of the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia. Mineralogical Magazine, 75, 2563-2572.
Internet Links for Megawite
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https://www.mindat.org/min-39893.html
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Localities for Megawite
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The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Russia (TL) | |
| Galuskin, E.V., Galuskina, I.O., Gazeev, V.M., Dzierżanowski, P., Prusik, K., Pertsev, N.N., Zadov, A.E., Bailau, R. & Gurbanov, A.G. (2011): Megawite, CaSnO3: a new perovskite-group mineral from skarns of the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia. Mineralogical Magazine, 75, 2563-2572. |
Xenolith no. 3, Lakargi Mt., Upper Chegem volcanic caldera, Baksan Valley, Kabardino-Balkarian Republic, Northern Caucasus Region, Russia